The present invention refers to gear change devices for motor vehicles, of the type comprising:                a first and a second primary shaft coaxial with respect to each other, selectively connectable to the driving shaft of the motor vehicle by means of a double clutch engagement device,        a first and a second secondary shaft, whose axes are parallel and spaced from the common axis of said primary shafts, and having respective output gear wheels intended to mesh with the gear wheel of a differential,        a plurality of pairs of gear wheels, corresponding to a plurality of forward gear ratios and to at least one reverse gear ratio, wherein the gear wheels of each pair are one rigidly connected in rotation with one of the primary shafts or with one of the secondary shafts while the other is freely rotatable on one of the secondary shafts or on one of the primary shafts respectively,        a plurality of gear selector devices for rotatably coupling each of said freely rotatable gear wheels with the shaft on which it is mounted,        wherein the reverse gear ratio is defined by:                    a first reverse gear wheel mounted freely rotatable on the first secondary shaft and connectable in rotation with the latter by means of one of said selector devices, with the aim of selecting the reverse gear,            a second reverse gear wheel, which serves as an idler gear wheel for inverting the motion, which meshes with said first reverse gear wheel and which is mounted freely rotatable on the second secondary shaft, said second reverse gear wheel being permanently connected in rotation with a forward gear wheel which is mounted freely rotatable on the abovementioned second secondary shaft and meshes with a gear wheel rotatably rigidly connected on one of said primary shafts,                        wherein a parking gear wheel is operatively connected to said first secondary shaft cooperating with a lock device for locking the gear change device in the parking condition.        
A gear change device of the above indicated type is described in DE 10 2004 056 936 and in the corresponding U.S. Pat. No. 7,690,278 B2 and WO 2006/0563252.